NAND flash memory, as well as other types of non-volatile memories (“NVMs”), are commonly used for mass storage. For example, consumer electronics such as portable media players often include flash memory to store music, videos, and other media.
Non-volatile memories, however, may develop defective memory cells through everyday use. For example, operational memory cells may suffer from read disturbs due to repeated read operations of neighboring cells. When a memory location, such as a page, of a NVM contains too many defective cells, the information contained within that memory location may be lost.
Conventionally, in order to prevent information loss due to read disturbs, a block of the NVM can be relocated after a fixed number of read operations have been performed on the block. During the relocation process, data contained in the block can be copied to another block of the NVM. Unfortunately, unnecessary relocations increase the number of writes that must be performed on the NVM and can consequently shorten the lifespan of the NVM.